PROJECT SUMMARY/ABSTRACT Male circumcision provides partial protection against HIV acquisition in heterosexual men. In 2010, Tanzania launched a National Strategy for scaling up male circumcision, which aims to circumcise 2.8 million males by 2015. During a recent PEPFAR-funded campaign by Jhpiego in Iringa region, over 10,000 males were circumcised in six weeks. In line with the national strategy the target age for the campaign was 10-34 years, but 80% of clients were aged 10-19 years. This is a cause for concern, as modelling studies suggest that the greatest population-level benefit of circumcision on HIV incidence will be achieved by circumcising men in their 20s and 30s, when HIV incidence is highest. The goal of our proposed study is to increase uptake of circumcision among older men (age 20- 34 years). Our specific aims are to refine, implement and evaluate a strategy to increase the uptake of circumcision among males aged 20-34 years in Iringa and Tabora regions, Tanzania. The strategy is based on Information-Motivation-Behavioral Skills (IMB) theory. We will conduct a qualitative study to identify barriers and facilitating factors to uptake of male circumcision services among males aged 20-34 years in Iringa and Tabora regions; use these findings to refine and pilot a targeted strategy to increase circumcision uptake in this age group; and evaluate the effectiveness of the intervention on the number and proportion of male clients aged 20-34 through a cluster randomized controlled trial (RCT). The research will build upon and be conducted alongside Jhpiego's ongoing circumcision provision in Tanzania. For the RCT, sixteen facilities providing circumcision services and their surrounding communities will be randomized to either the intervention group (those in which the targeted strategy will be implemented) or the control group (providing the standard circumcision provision package). Data will be collected from each clinic for a 4 week period during the 2012 Tanzanian circumcision season (June-August). The primary outcomes will be the proportion of circumcision clients who are aged 20-34 years, the mean weekly number of clients in this age group, and the cost per client of the intervention. The proposed operational research will provide timely evidence on whether a community-based strategy can provide a cost-effective method of increasing the proportion and number of male circumcision clients aged 20-34 years in Tanzania. If successful, the resulting strategy can be translated into routine and common practices throughout Tanzania and in other countries.